be good to see pics first to see what it loks like

its pretty easy to mount an L series in without sump mods...you just sit it way high and use a bluebird or 200b sump(which ever is the smaller one)

it wont be any kind of standard crossmember, will most likely just have stock looking mounts welded onto a 1200 crossmember

the way ive done it, as a comparison, is to dump the engine down as far as it can possibly go before it hits the drag link, this required notching the crossmember about 15-20mm in the middle and making a very custom sump that was alot shallower at the bock for extra clearance to the drag link and crossmember. at full lock the drag link just clears the sump
then was low enough to fit th L20b with stock air box on it and a spacer under the carby so i could run cable accelorator not linkages like the 200b did. its a good 5-10mm of extra spacer that you wouldnt normally have
also modded 200b engine mounts, that bolt to the engine, so that the engine sits lower than it normally would. this was more to allow the mounts on the crossmember to be big enough to get your hand in to do up the bottom engine mount bolt


not to put your idea down or anything but in my experience the mounts were one of the easier things to do in the conversion

just to be clear....not putting your idea down just adding my thoughts/experience